Fist bump, handshake, high-five: Which spreads the most germs?

Fist bumping, a form of greeting popularized by President Obama, spreads significantly fewer germs than the more traditional alternative, according to a new study.

A fist bump transmits just one-twentieth the amount of bacteria that a handshake does. It is also a less germy option than a high-five, which still spreads less than half the amount of germs typically spread through a handshake, the new research found.

In the study, published in the August issue of the American Journal of Infection Control, researchers wanted to see whether alternative greetings would transmit fewer germs than the traditional handshake. One greeter immersed a sterile-gloved hand into a container of germs. One the glove was dry, the greeter exchanged a handshake, fist bump or high-five with a sterile-gloved recipient. Then the researchers examined the number of bacteria on transferred during the experiment.

"Adoption of the fist bump as a greeting could substantially reduce the transmission of infectious diseases between individuals," study author David Whitworth of Aberystwyth University in the United Kingdom said in a statement. "It is unlikely that a no-contact greeting could supplant the handshake; however, for the sake of improving public health we encourage further adoption of the fist bump as a simple, free, and more hygienic alternative to the handshake."

A fist bump is more sanitary than a handshake because of the smaller amount of surface area in contact between the two hands, the study suggests.

"It's a novel study," though the results are not surprising, said Mary Lou Manning, president-elect of the Association for Professionals in Infection Control and Epidemiology. Manning's organization publishes the journal.